This is based on the zinc white colour found on a window salvaged from Cambridge. Original window obtained from the Charles Brooking Collection. This is the colour used on the Russian Cottage on Chatsworth Estate.
Coverage is approx 15-20 m2, which equates to about £ 3.30 / m2 for the finished job (done in 3 coats).
For Farrow & Ball Exterior Eggshell (+ primer) this is approx £ 6.46 and for Dulux Trade Exterior approx £ 4.14.